Return The Size Of An Open BLOB

int sqlite3_blob_bytes(sqlite3_blob *);

R-07796-55423:[Returns the size in bytes of the BLOB accessible via the
successfully opened BLOB handle in its only argument.]R-53088-19343:[The
incremental blob I/O routines can only read or overwriting existing
blob content; they cannot change the size of a blob.]

This routine only works on a BLOB handle which has been created
by a prior successful call to sqlite3_blob_open() and which has not
been closed by sqlite3_blob_close(). Passing any other pointer in
to this routine results in undefined and probably undesirable behavior.